Simultaneously with the modernity movement and the beginning of modernism in Iran, a change in the structure of the narrative and visual expression of Ashura themes appeared, and artists tried to present these concepts in a new format by integrating tradition and modernity and by using the appearance of patterns and symbols. As a tool that is compatible with the spirit of the times, the poster plays an important role in presenting Ashura concepts. Based on this, Ashura mourning posters became a possibility to keep alive and honor the high values ​​of that history-making epic. It can be said that the initial origins of Ashura posters go back to coffeehouse painting (imaginary art) and Ta'zieh curtains during the Safavid and Qajar periods. With the onset of the modern movement in the West and modernist trends in Iranian painting, graphic design was also influenced and found an opportunity to emerge. Among graphic designs, the poster is the most effective for conveying Ashura concepts. The designer conveys their intended message using graphic visual elements in the poster. The present research aims to analyze and investigate modernity in the structure of Ashura mourning posters. Therefore, the question here is how modernity affects the visual and narrative structure of Ashura mourning posters. The present research is applied in terms of its purpose and descriptive-analytical in terms of its method. The data collection method is based on library documents and records, which were collected and categorized using tools such as index cards, photographs, the internet, and tables. Accordingly, the study introduces the background of Ashura posters in a brief description, and then it analyzes the impact of modernity in changing the visual and narrative structure of these posters. The statistical population of 22 posters, whose concepts are divided into two groups, traditionalist and modernist, based on reliability and validity, has been selected from fourteen periods of Ashura mourning posters and analyzed and compared. The results of the studies indicate that with the arrival of the modernity movement in Iran and the beginning of modernism trends, the arts were consciously breaking away from their past in search of new forms of expression. Therefore, modernism caused a change in the artist's technique, form, and attitude. In the structure of Ashura posters in a traditional way, the designer has used explicit and direct meaning to tell the concepts of Ashura in the visual expression of the posters. For this purpose, he tried to use more realistic photos, icons, and coffee house paintings and pay attention to the details and decorations according to the background of Iranian painting art. With the emergence of modernism in Iranian art, graphics also underwent changes. During this period, a new visual and narrative structure emerged in Ashura posters. Under the influence of Western art schools and international events, modern designers tried to replace realism with an abstract attitude instead of portraying in traditional ways. Among the impacts that modernism has had on the visual structure of Ashura posters is the diversity in calligraphy, which is considered the main element of visual expression for Ashura themes. Flat and uniform colors, minimal use of symbolic elements in the poster, abstraction and simplicity in expression, strong contrast in the use of surface, color, and negative space, creativity and innovation in ideas and the artist's personal genius as well as in the work itself, and the use of non-religious and non-denominational symbols for symbolic and metaphorical expression of Ashura concepts are other influences of modernism on Ashura posters. According to the structuralists, what leads to a change in the structure ultimately causes a change in meaning and nature. It can be said that Ashura posters, which previously expressed a traditional and religious spirit, have transformed into posters that have acquired a modern essence, and their historical religious orientation has become a modern historical orientation due to changes in narrative structure. It is worth noting that due to the oversimplification of the form, some posters have taken on an abstract appearance, thus prioritizing the formal aspect over the Ashura concepts. Consequently, they may not be able to express the religious values of the Ashura event. In addition to the cases mentioned, it can be said that modernization in the expression of Ashura posters has also brought positive points. Because this simplicity and change of symbols to present concepts can cause thinking and improve the level of visual literacy of the audience and society.